they have agreed to rule on the question, do same sex couples have a right to get married under the u.s. constitution? it will be a history-making decision, and surprisingly, it's an 83-year-old woman at the center of this case. and abc's expert on the supreme court, terry moran, is here right now. terry? >> reporter: well, diane, constitutionally, it doesn't get any bigger than this. the country's changed so much on this issue. the real question is, how much? and, like so many landmark cases, as you point out, this one begins with the story of one american. this case is going to go down in history as edie windsor versus the united states. edie windsor, 83 years old, is a widow now. but she had 42 happy years with the love of her life -- thea spyer. >> she was beautiful. she was smart as hell. and she was wonderful altogether. >> reporter: edie and thea were married but when thea died in 2009, edie got socked by the irs with $363,000 in estate taxes, which no widow in a straight marriage would have to pay. today, the supreme court decided to hear edie's case challenging the law she says